Boat transmission

ABSTRACT

The multi-speed boat transmission for propulsion systems having a basic transmission for transmitting the motor power to a fixed propeller or water jet has, in addition to a preferably single-speed basic transmission ( 2 ), a separate front-mounted transmission ( 1 ) for flange-mounting to the basic transmission ( 2 ) and stepping-up parts ( 7, 8, 12 ), the countershafts ( 5 ) being distributed around the periphery of the main shaft ( 10 ) of the basic transmission in a manner such that no additional forces act upon the main shaft ( 10 ).

FIELD OF THE INVENTION

The invention relates to a multi-speed boat transmission.

BACKGROUND OF THE INVENTION

In conventional,boat transmissions, a fixed propeller is driven by amotor via a transmission having a constant ratio. The consequence ofthis construction is that the propulsion system can be optimallycoordinated only for one operating point.

However, there are often situations in which such constructions have anunfavorable effect: when, e.g. the propulsion system is designed for afinal speed as high as possible, the motor is pressed relative to therotational speed when the boat resistance is increased as a result ofweather conditions, cargo, etc. whereby only one part of the total powerof the motor is available. Besides, the acceleration properties are poorand the thermal load of the motor is high. This also results in theproduction of soot.

On the other hand, if the propulsion system is designed for anacceleration as high as possible or for driving with elevatedresistance, the nominal rotational speed of the motor under normalconditions is achieved without delivering full power in the process.This has a negative effect on the final speed obtainable.

It thus becomes necessary to optimize the propulsion device so that itis adaptable to different conditions of operation whereby the motor canalways work in an optimal rotational speed range.

To that end, a variable-pitch propeller has been proposed. But thissolution mechanically requires much expenditure and, consequently, isexpensive and unusual in yachts/speed boats. A variable-pitch propelleralso has poor efficiency.

SUMMARY OF THE INVENTION

DE 196 24 913 A1 discloses a marine propeller system having one motor,one shifting mechanism and one programmable electronic control devicewith a shifting parameter matrix. The electronic control device monitorsthe motor load and the revolution rate and produces a control signalwhich controls the shifting operations. Since this system forms oneunit, it is not possible to change over already existing transmissionsof the conventional kind mentioned above. On the contrary, newtransmissions must be developed according to those requirements.

DE 31 02 556 A1 discloses a two-step transmission for boat propellersystems in which a planetary transmission is used. This transmission hasa direct gear with a 1:1 ratio shiftable by a friction clutch for thecruising drive, while for a drive at highest speed a high speed gear isprovided which is formed by the planetary transmission and a hydraulicclutch, and gears up the rotational speed.

With this construction, it is not possible to implement any small speedratio changes for the high-speed range: likewise a simple change of theratio is not possible. Furthermore, losses occur in the highest speedrange.

Therefore, the problem on which this invention is based is to make apower shiftable boat transmission available which, in combination with afixed propeller or water jet, allows a variable adaptation to differentoperating conditions.

Accordingly, on an already existing basic transmission, it is proposedto flange mount a separate front-mounted transmission having at leasttwo countershafts wherein the countershafts are distributed around theperiphery of the main shaft of the basic transmission in a manner suchthat no additional forces act upon the main shaft. The front-mountedtransmission can be flange mounted on different transmission designs ofboat propelling families without having to develop entirely newtransmissions, therefore, the possible uses are multiple.

In addition, the front-mounted transmission is modularly built so thatit can be coordinated by adapting a few parts to different operatingconditions without having to develop new transmissions.

Besides, the stepping-up parts are configured in such a way that, via aprovided plug-in system, it is possible to prepare both a gear up and agear down ratio, with identical parts, but by a different assembly.Moreover, by varying the number of individual stepping-up parts teeth,different ratio ranges can be implemented. Moreover, by varying thenumber of individual stepping-up parts teeth, different ratio ranges canbe implemented.

All this requires only a small assembly expenditure wherein almostarbitrary ratios can be implemented and, in particular, small ratiochanges are also possible, unlike in a planetary transmission.

The construction proposed is of reasonable cost, since in most casesonly a different assembly of identical parts is needed. It also offers ahigh measure of flexibility in regard to different requirements.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in detail with the aid of the drawings whichshow:

FIG. 1a is a power-rotational speed diagram of a conventional boatpropeller designed for high final speed;

FIG. 1b is a power-rotational speed diagram of a conventional boatpropeller designed for high acceleration;

FIG. 2 is a cross-sectional representation of the front-mountedtransmission according to a first variant of the instant invention;

FIG. 3 is a cross-sectional representation of the front-mountedtransmission according to a second variant of the instant invention;

FIG. 4 is a cross-sectional representation of the front-mountedtransmission according to a third variant of the instant invention.

FIG. 1a makes clear the need to adapt a boat propulsion system todifferent operating conditions:

DESCRIPTION OF THE PREFERRED EMBODIMENTS

If the propulsion system has been laid out for the highest possiblefinal speed, the optimal operating point A, at a correspondingly highmotor rotational speed n, is in the proximity of the nominal rotationalspeed n_max, which, in turn, results in a high generated power P in theproximity of the maximum power P_max. Under great boat resistanceresulting from weather conditions, cargo, etc., the motor is pressedrelative to the rotational speed and the optimum operating point cannotbe reached. The new operating point A′ stands out by the fact that onlya part of the total power of the motor is available. Besides, theacceleration property is poor and the thermal load of the motor high.This also results in the production of soot.

FIG. 1b illustrates another typical unfavorable situation: in the caseshown, the propulsion system is laid out for high acceleration or highboat resistance. Thereby under normal conditions, the motor reaches thenominal rotational speed n_max at the operating point B withoutgenerating the full power P_max.

According to FIG. 2, a front-mounted transmission is flange-mounted on abasic transmission 2. The motor drives a shaft 3. According to theinvention, it is possible, via a clutch 4, to completely shift directlyto the basic transmission, the ratio amounting to 1:1 or alternativelyto select one other ratio i by means of both countershafts 5. The ratiois activated by means of one other clutch or of one free wheel unit 6.By virtue of the free wheel unit, the load is mechanically taken upautomatically.

By virtue of the construction described here as a front-mountedtransmission with power distribution over two symmetrically oppositecountershafts 5, no added forces act upon the basic transmission 2,since the supporting forces of the main shaft 10 have been removed. Nochanges of the housing or of the support are therefore needed.

Within the scope of this special advantageous embodiment of the instantinvention, helical-cut teeth are provided for noise reasons. In thiscase, in order to keep the main shaft 10 free of additional forces,pressure cams 11 are provided which assist generating axial forces ofthe main shaft wheels.

Between the gear ring of the helical-cut toothing 12 of thecountershafts 5 and the main shaft 10, a flexible annular connectingelement 8 is provided of which one end meshes with the gear ring and theother end is connected with the main shaft 10, a flexible area beingprovided between the two ends. The flexible area preferably has areduced wall thickness.

By adequate selection of the stepping-up parts 7 and 8, an optionalgradation of the gears is possible so that an optimal coordinationbetween motor and transmission can be obtained: to implement one otherratio, only toothing parts 12 have to be exchanged.

In addition, the stepping-up parts of the inventive front-mountedtransmission are designed so that it is possible to obtain a ratio 1/ireciprocal with the initial ratio i via a provided plug-in system 9 by adifferent assemblage with identical parts.

This situation is shown in FIG. 3: Due to the opposite orientation ofthe countershafts 5 and to an adequate assembly of the parts 7 and 8,and of the clutch and free-wheel devices 4 and 7, a ratio 1/i isobtained.

To this end, the stepping-up parts 7, 8, by means of a plug-in system 9,can be plugged and fixed respectively on the shaft 3 driven by the motorand the main shaft 10 of the basic transmission 2.

The selection of the power shift can also be implemented without freewheel by using two regulated multi-disc clutches 4, 4′. This isillustrated in FIG. 5: via the multi-disc clutch 4′, it is possible tocompletely shift to the basic transmission while, via the clutch 4, thepower is distributed to the countershafts 5. The ratio obtained by thereproduced construction can be changed without much expenditure: to thisend, the stepping-up parts are differently mounted, as explainedalready, whereby it is possible to achieve a ratio reciprocal to theinitial one.

Although a two-speed transmission has been described, multi-speedtransmissions are also conceivable by means of the front-mountedconstruction of the transmission that has been described. The inventionIs not confined to a multi-speed boat transmission which has a separatebasic transmission. A housing can be provided which comprises all ratiosteps including those of the basic transmission. Depending on the kindof propulsion or total ratio required, a basic transmission can beentirely omitted. For this purpose, only the shaft connections have tobe adapted. FIG. 3 shows such a transmission.

REFERENCE NUMERALS

1 front-mounted transmission

2 basic transmission

3 shaft

4 clutch

5 countershaft

6 free wheel

7 stepping-up part

8 stepping-up part, flexible connecting element

9 plug-in system

10 main shaft

11 pressure cam

12 helical-cut toothing

What is claimed is:
 1. A multi-speed boat transmission for a propellersystem to transmit a power from a motor to one of a fixed propeller anda water jet, the multi-speed boat transmission comprising: a drive shaft(3) for supplying driving power from a motor to the multi-speed boattransmission; at least two countershafts (5) distributed around aperiphery of a main shaft (10) and the driving shaft (3); and at leasttwo stepping-up parts (7, 8, 12); wherein the at least two countershafts(5) and the at least two stepping-up parts (7, 8) have 9 first mountableorientation in which the at least two stepping-up parts (7, 8) generatea first ratio, and the at least two countershafts (5) and the at leasttwo stepping-up parts (7, 8) have a second mountable orientation, whichis opposite to the first mountable orientation, in which the at leasttwo stepping-up parts (7, 8) generate a second ratio that is differentfrom the first ratio.
 2. The multi-speed boat transmission according toclaim 1, wherein the at least two stepping-up parts (7, 8) comprise aplug-in system and the plug-in system is removably fixed to both thedrive shaft (3) and the main shaft (10).
 3. The multi-speed boattransmission according to claim 1, wherein each of the at least twocountershafts (5) and the at least two stepping-up parts (7, 8) havehelically cut teeth (12) with helix angles coordinated to cancel outaxial forces generated by each of the at least two countershafts (5) andthe at least two stepping-up parts (7, 8) during operation of themulti-speed boat transmission.
 4. The multi-speed boat transmissionaccording to claim 1, wherein the multi-speed boat transmission furthercomprises a first clutch (4′) and a second clutch (4) and, uponactuation of the first clutch (4′), direct drive to the main shaft (10)is achieved and, upon actuation of the second clutch (4), power isbranched off from the drive shaft (3), via the countershafts (5), inorder to achieve one of the first and the second ratios.
 5. Themulti-speed boat transmission according to claim 1, wherein themulti-speed boat transmission further comprises a clutch (4) and a freewheel (6), wherein, upon actuation of the clutch (4), direct drive tothe main shaft (10) is achieved and, upon operation of the free wheel(6), the power is branched off via the countershafts (5) and load isautomatically taken up mechanically.
 6. The multi-speed boattransmission according to claim 1, wherein the multi-speed boattransmission comprises a two-speed transmission.
 7. The multi-speed boattransmission according to claim 1, wherein the multi-speed boattransmission comprises a separate front-mounted transmission (1) mountedto a basic transmission (2).
 8. A multi-speed boat transmission for apropeller system to transmit a power from a motor to one of a fixedpropeller and a water jet, the multi-speed boat transmission comprising:a drive shaft (3) for supplying driving power from a motor to themulti-speed boat transmission; at least two countershafts (5)distributed around a periphery of a main shaft (10) and the drivingshaft (3); and at least two stepping-up parts (7, 8, 12); wherein eachof the at least two countershafts (5) and the at least two stepping-upparts (7, 8) have helically cut teeth (12), the at least twocountershafts (5) are distributed around the periphery of the main shaft(10) and a pair of pressure cams (11) are supported by each one of theat least two countershafts (5) to keep the main shaft (10) free of axialforces.
 9. The multi-speed boat transmission according to claim 8,wherein helically But teeth (12) of the at least two countershafts (5)and the at least two stepping-up parts (7, 8) have helix anglescoordinated to cancel out axial forces generated by the at least twocountershafts (5) and the at least two stepping-up parts (7, 8),duringoperation of the multi-speed boat transmission.
 10. The multi-speed boattransmission according to claim 8, wherein the multi-speed boattransmission further comprises a first clutch (4′) and a second clutch(4) and, upon actuation of the first clutch (4′), direct drive to themain shaft (10) is achieved and, upon actuation of the second clutch(4), power is branched off from the drive shaft (3), via thecountershafts (5), in order to achieve another ratio.
 11. Themulti-speed boat transmission according to claim 8, wherein themulti-speed boat transmission further comprises a clutch (4) and a freewheel (6), wherein, upon actuation of the clutch (4), direct drive tothe main shaft (10) is achieved and, upon operation of the free wheel(6), the power is branched off via the countershafts (5) and load isautomatically taken up mechanically.
 12. The multi-speed boattransmission according to claim 8, wherein the multi-speed boattransmission comprises a two-speed transmission.
 13. The multi-speedboat transmission according to claim 8, wherein the multi-speed boattransmission comprises a separate front-mounted transmission (1) mountedto a basic transmission (2).
 14. A multi-speed boat transmission for apropeller system to transmit power from a motor to one of a fixedpropeller and a water jet, the multi-speed boat transmission comprising:at least two countershafts (5) distributed around a periphery of a mainshaft (10); and at least two stepping-up parts (7, 8, 12); wherein eachof the at least two countershafts (5) and the at least two stepping-upparts (7) have helically cut teeth (12), one (8) of the at least twostepping-up parts (7, 8) is a flexible annular connecting element, theflexible annular connecting element has a first end meshing with thetoothing of the at least two countershafts (5) and a second end meshingwith toothing of one of the main shaft (10) and a drive shaft (3), andthe flexible annular connecting element has a flexible area providedbetween the first and second ends.
 15. The multi-speed boat transmissionaccording to claim 14, wherein the flexible area is a segment which hasa reduced wall thickness compared to a wall thickness of the first endand the second end of the flexible annular connecting element.
 16. Themulti-speed boat transmission according to claim 14, wherein helicallycut teeth (12) of the at least two countershafts (5) and the at leasttwo stepping-up parts (7, 8) have helix angles coordinated to cancel outaxial forces generated by the at least two countershafts (5) and the atleast two stepping-up parts (7, 8) during operation of the multi-speedboat transmission.
 17. The multi-speed boat transmission according toclaim 14, wherein the multi-speed boat transmission further comprises afirst clutch (4′)and a second clutch (4) and, upon actuation of thefirst clutch (4′), direct drive to the main shaft (10) is achieved and,upon actuation of the second clutch (4), power is branched off from thedrive shaft (3), via the countershafts (5), in order to achieve anotherratio.
 18. The multi-speed boat transmission according to claim 14,wherein the multi-speed boat transmission further comprises a clutch (4)and a free wheel (6), wherein, upon actuation of the clutch (4), directdrive to the main shaft (10) is achieved and, upon operation of the freewheel (6), the power is branched off via the countershafts (5) and loadis automatically taken up mechanically.
 19. The multi-speed boattransmission according to claim 14, wherein the multi-speed boattransmission comprises a two-speed transmission.
 20. The multi-speedboat transmission according to claim 14, wherein the multi-speed boattransmission comprises a separate front-mounted transmission (1) mountedto a basic transmission (2).